Suchergebnisse

Comunicación presentada en el International Congress Science and Technology for the Conservation of Cultural Heritage (TechnoHeritage), celebrado en Santiago de compostela del 2 al 5 de octubre de 2012. ; Sulfate attack by ground waters, soils, etc. is one of the threats to the built heritage in concrete. This study validated through thermodynamic modeling with GEMS geochemical code a new sulfate-resistant formulation based on the addition of BaCO3 and BaO to ordinary Portland cement (OPC), which could be used to replace weathered concrete. The thermodynamic calculations pointed out that Ba ions were able to form an insoluble salt, barite (BaSO4) with the dissolved sulfate which inhibited the formation of ettringite, the latter oc- curred when the concentrations of BaCO3 and BaO were ≥ 6 and ≥ 4 wt.%, respectively. The results of a simulated sulfate a ttack revealed that ettringite precipitated upon ingression of ≥46 ml of a Na2SO4 solution (44 wt.%) in OPC blends with 20 wt.% of BaCO3; whereas with 20 wt.% of BaO, the sulfate that precipitated besides ba rite was monosulfoaluminate when sulfate solution was ≥40 ml (tested up to 52 ml). ; Funding from the Spanish Ministry of Education and Science (Project CONSOLIDER CSD2007-00058) and the Regional Government of Madrid (Geomaterials Programme) is gratefully acknowledged. ; Peer Reviewed